1. Field of the Invention
The present invention is in the field of calcining of lime, dolomite, and similar materials used in the manufacture of cement. It involves a modification of the conventional system in which the raw material to be calcined is preheated, calcined, and then cooled.
2. Description of the Prior Art
In German Pat. No. 1,218,927 there is shown a method and apparatus for calcining lime, dolomite, and the like in which combustion air which has been preheated in the cooler is supplied to a calcining chamber and is utilized there. Following the calcining chamber, the combustion gas stream generated therein is divided into two sub-streams which are used to thermally treat the input raw material in the desired manner in horizontal calcining segments. Bypass conduits provided with throttle valves and the like divide the combustion gases emerging from the combustion chamber into individual sub-streams. Disposed at the end of the calcining segments are cyclones from which the calcined product proceeds into the cooler. A circulating cycle is provided for a portion of the combustion gases and of the calcined material.